1951 Crosley Model 11-119U Radio

[Captainclock]

Hello everyone, Saturday I went to my local Antique mall and was looking around and I spotted an old 1950s vintage AA5 radio on a shelf that was a light blue color and was in pretty decent shape yet for its age (minus a little dirt on the cabinet) so I picked it up and sure enough it was an old Crosley which I thought was kind of interesting because I've never seen an original Crosley Radio from the 1950s in person before (that's how rare the original Crosleys are) and to be exact it was a 1951 Crosley Model 11-119U which from what little research I was able to do on the 11-11xU line series of radios they were given away for free with the purchase of a Crosley Refrigerator back in the day and "light blue" colored one like I found was referred to as Smoke Blue colored and was actually rarest of the 11-11xU series of radios because of the fact that the Smoke Blue units were made specifically as the promotional models whereas the other models (the 11-115U-118U models were actually made as regualar retail models as well that could be bought at the store making them more common.) Anyways my unit for some reason had a large cotton ball glued to the back of the speaker for some reason when I got it and when I took it apart to check the unit out (it was sold "as is" not working) I had figured out that the 12AV6 tube was missing for some reason so then I installed a 12AV6 tube into the empty socket and powered the unit on and sure enough it powered on albeit with an incredibly loud hum, So I shut the unit down and unplugged it and figured out that I needed to replace the power supply caps (which the unit is actually now on its third round of power supply filter caps because the original caps had already been replaced previously at least 30+ years ago as it had an old Pyramid 40 + 40 @ 150 Volts electrolytic cap in there that was obviously not original as the "mounting bracket" for the replacement cap was soldered onto the old filter caps mounting bracket that had previously been cut off at the chassis), And I replaced the old replacement cap with a replacement cap I had laying around in an old radio I had previously recapped but then failed to opoerate properly inspite of the recap so it was then used as a parts unit.

Anyways once I replaced the old power supply caps with my new ones I had the unit powered up nicely and played perfectly except that for some reason when I removed the old cottonball out of the back of the speaker the speaker started "rattling" when it was pushed past a certain volume level so then to stop the "rattling" I ended up stuffing another cottonball into the back of the speaker which has of course muffled the speaker so that now its not as loud as its supposed to be.

Anyways what I'm curious about is what would be causing the speaker to "rattle around" when its pushed past a certain volume level? And why would a cottonball shoved into the back of the speaker fix this particular ailment?

Also is it true what I had read (and also mentioned earlier in the post) that original Crosleys are extremely rare and highly sought after?